The therapeutic and psychotropic effects of deltal-9-tetrahydrocannabinol (-90THC), the active principal in marijuana, have been known for centuries but not until recently has the mechanism of marijuana action been revealed. A specific receptor that bound -9-THC and other cannabinoids was recently cloned and sequenced at the NIMH suggesting that mimics the effects of marijuana use. An enigenous cannabinoid receptor agonist was recently isolated from porcine brain by William Devane while at the Hebrew University in Jerusalem. This novel cannabimimetic eicosanoid was found to be a condensation of arachidonic acid with ethanolamine in an amide linkage and was given the name anandamide, a Indiam Sanskrit word meaning internal bliss. Fatty acid amides, such as anandamide, may represent a novel group of neurotransmitters in that they are too fat soluble to be stored in vesicles within the nerve terminal like classical neurotransmitters. Anadamide appears to be made on demand and diffuses out of the nerve to bind to cannabinoid receptors on the same or possibly neighboring cells. the role of anadamides and naccabinoid receptors in normal brain function is not presently known. We have also discovered a drug which blocks cannabinoid receptors which may provide clues about the physiologic role of the novel "anandaregic" nervous system.